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Merge branch 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  perf: Fix the software context switch counter
  perf, x86: Fixup Kconfig deps
  x86, perf, nmi: Disable perf if counters are not accessible
  perf: Fix inherit vs. context rotation bug
master
Linus Torvalds 11 years ago
parent
commit
a9e40a2493
  1. 2
      arch/x86/Kconfig
  2. 20
      arch/x86/kernel/cpu/perf_event.c
  3. 30
      include/linux/perf_event.h
  4. 24
      kernel/perf_event.c

2
arch/x86/Kconfig

@ -21,7 +21,7 @@ config X86
select HAVE_UNSTABLE_SCHED_CLOCK
select HAVE_IDE
select HAVE_OPROFILE
select HAVE_PERF_EVENTS if (!M386 && !M486)
select HAVE_PERF_EVENTS
select HAVE_IRQ_WORK
select HAVE_IOREMAP_PROT
select HAVE_KPROBES

20
arch/x86/kernel/cpu/perf_event.c

@ -381,6 +381,20 @@ static void release_pmc_hardware(void) {}
#endif
static bool check_hw_exists(void)
{
u64 val, val_new = 0;
int ret = 0;
val = 0xabcdUL;
ret |= checking_wrmsrl(x86_pmu.perfctr, val);
ret |= rdmsrl_safe(x86_pmu.perfctr, &val_new);
if (ret || val != val_new)
return false;
return true;
}
static void reserve_ds_buffers(void);
static void release_ds_buffers(void);
@ -1372,6 +1386,12 @@ void __init init_hw_perf_events(void)
pmu_check_apic();
/* sanity check that the hardware exists or is emulated */
if (!check_hw_exists()) {
pr_cont("Broken PMU hardware detected, software events only.\n");
return;
}
pr_cont("%s PMU driver.\n", x86_pmu.name);
if (x86_pmu.quirks)

30
include/linux/perf_event.h

@ -850,6 +850,7 @@ struct perf_event_context {
int nr_active;
int is_active;
int nr_stat;
int rotate_disable;
atomic_t refcount;
struct task_struct *task;
@ -908,20 +909,6 @@ extern int perf_num_counters(void);
extern const char *perf_pmu_name(void);
extern void __perf_event_task_sched_in(struct task_struct *task);
extern void __perf_event_task_sched_out(struct task_struct *task, struct task_struct *next);
extern atomic_t perf_task_events;
static inline void perf_event_task_sched_in(struct task_struct *task)
{
COND_STMT(&perf_task_events, __perf_event_task_sched_in(task));
}
static inline
void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next)
{
COND_STMT(&perf_task_events, __perf_event_task_sched_out(task, next));
}
extern int perf_event_init_task(struct task_struct *child);
extern void perf_event_exit_task(struct task_struct *child);
extern void perf_event_free_task(struct task_struct *task);
@ -1030,6 +1017,21 @@ have_event:
__perf_sw_event(event_id, nr, nmi, regs, addr);
}
extern atomic_t perf_task_events;
static inline void perf_event_task_sched_in(struct task_struct *task)
{
COND_STMT(&perf_task_events, __perf_event_task_sched_in(task));
}
static inline
void perf_event_task_sched_out(struct task_struct *task, struct task_struct *next)
{
perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
COND_STMT(&perf_task_events, __perf_event_task_sched_out(task, next));
}
extern void perf_event_mmap(struct vm_area_struct *vma);
extern struct perf_guest_info_callbacks *perf_guest_cbs;
extern int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *callbacks);

24
kernel/perf_event.c

@ -1287,8 +1287,6 @@ void __perf_event_task_sched_out(struct task_struct *task,
{
int ctxn;
perf_sw_event(PERF_COUNT_SW_CONTEXT_SWITCHES, 1, 1, NULL, 0);
for_each_task_context_nr(ctxn)
perf_event_context_sched_out(task, ctxn, next);
}
@ -1622,8 +1620,12 @@ static void rotate_ctx(struct perf_event_context *ctx)
{
raw_spin_lock(&ctx->lock);
/* Rotate the first entry last of non-pinned groups */
list_rotate_left(&ctx->flexible_groups);
/*
* Rotate the first entry last of non-pinned groups. Rotation might be
* disabled by the inheritance code.
*/
if (!ctx->rotate_disable)
list_rotate_left(&ctx->flexible_groups);
raw_spin_unlock(&ctx->lock);
}
@ -6162,6 +6164,7 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
struct perf_event *event;
struct task_struct *parent = current;
int inherited_all = 1;
unsigned long flags;
int ret = 0;
child->perf_event_ctxp[ctxn] = NULL;
@ -6202,6 +6205,15 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
break;
}
/*
* We can't hold ctx->lock when iterating the ->flexible_group list due
* to allocations, but we need to prevent rotation because
* rotate_ctx() will change the list from interrupt context.
*/
raw_spin_lock_irqsave(&parent_ctx->lock, flags);
parent_ctx->rotate_disable = 1;
raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
list_for_each_entry(event, &parent_ctx->flexible_groups, group_entry) {
ret = inherit_task_group(event, parent, parent_ctx,
child, ctxn, &inherited_all);
@ -6209,6 +6221,10 @@ int perf_event_init_context(struct task_struct *child, int ctxn)
break;
}
raw_spin_lock_irqsave(&parent_ctx->lock, flags);
parent_ctx->rotate_disable = 0;
raw_spin_unlock_irqrestore(&parent_ctx->lock, flags);
child_ctx = child->perf_event_ctxp[ctxn];
if (child_ctx && inherited_all) {

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